On Fri, 30 Sep 2016 14:43:25 +0200,
Subhransu S. Prusty wrote:
>
> From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
>
> When appl_ptr is updated let low-level driver know, e.g. to let the
> low-level driver/hardware pre-fetch data opportunistically.
>
> The existing .ack callback could be used but it would need to be
> extended with new arguments, resulting in multiple changes in legacy
> code.
I wouldn't mind changing these callers. They aren't so many, after
all.
Takashi
> Instead a new .appl_ptr_update callback is added. The difference
> between .ack and .appl_ptr_update is that .ack is only called on read or
> write. .appl_ptr_update is called on read, write, rewind, forward or
> when updating the appl_ptr from userspace.
>
> In the ALSA core, this capability is independent from the NO_REWIND
> hardware flag. The low-level driver may however tie both options and
> only use the updated appl_ptr when rewinds are disabled due to hardware
> limitations.
>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> Signed-off-by: Babu, Ramesh <ramesh.babu@xxxxxxxxx>
> Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
> Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@xxxxxxxxx>
> ---
> include/sound/pcm.h | 1 +
> sound/core/pcm_lib.c | 6 ++++++
> sound/core/pcm_native.c | 24 +++++++++++++++++++++++-
> 3 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/include/sound/pcm.h b/include/sound/pcm.h
> index 5344c16..1accb8b 100644
> --- a/include/sound/pcm.h
> +++ b/include/sound/pcm.h
> @@ -87,6 +87,7 @@ struct snd_pcm_ops {
> unsigned long offset);
> int (*mmap)(struct snd_pcm_substream *substream, struct vm_area_struct *vma);
> int (*ack)(struct snd_pcm_substream *substream);
> + int (*appl_ptr_update)(struct snd_pcm_substream *substream);
> };
>
> /*
> diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
> index bb12615..1656ca9 100644
> --- a/sound/core/pcm_lib.c
> +++ b/sound/core/pcm_lib.c
> @@ -2090,6 +2090,9 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
> if (substream->ops->ack)
> substream->ops->ack(substream);
>
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> offset += frames;
> size -= frames;
> xfer += frames;
> @@ -2322,6 +2325,9 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
> if (substream->ops->ack)
> substream->ops->ack(substream);
>
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> offset += frames;
> size -= frames;
> xfer += frames;
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index be8617b..c56d4ed 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -2475,6 +2475,10 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst
> appl_ptr += runtime->boundary;
> runtime->control->appl_ptr = appl_ptr;
> ret = frames;
> +
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> __end:
> snd_pcm_stream_unlock_irq(substream);
> return ret;
> @@ -2526,6 +2530,10 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr
> appl_ptr += runtime->boundary;
> runtime->control->appl_ptr = appl_ptr;
> ret = frames;
> +
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> __end:
> snd_pcm_stream_unlock_irq(substream);
> return ret;
> @@ -2575,6 +2583,10 @@ static snd_pcm_sframes_t snd_pcm_playback_forward(struct snd_pcm_substream *subs
> appl_ptr -= runtime->boundary;
> runtime->control->appl_ptr = appl_ptr;
> ret = frames;
> +
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> __end:
> snd_pcm_stream_unlock_irq(substream);
> return ret;
> @@ -2624,6 +2636,10 @@ static snd_pcm_sframes_t snd_pcm_capture_forward(struct snd_pcm_substream *subst
> appl_ptr -= runtime->boundary;
> runtime->control->appl_ptr = appl_ptr;
> ret = frames;
> +
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> +
> __end:
> snd_pcm_stream_unlock_irq(substream);
> return ret;
> @@ -2723,8 +2739,14 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
> return err;
> }
> snd_pcm_stream_lock_irq(substream);
> - if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL))
> + if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) {
> + /* boundary wrap-around is assumed to be handled in userspace */
> control->appl_ptr = sync_ptr.c.control.appl_ptr;
> +
> + /* let low-level driver know about appl_ptr change */
> + if (substream->ops->appl_ptr_update)
> + substream->ops->appl_ptr_update(substream);
> + }
> else
> sync_ptr.c.control.appl_ptr = control->appl_ptr;
> if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_AVAIL_MIN))
> --
> 1.9.1
>
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